The present embodiments relate to a system that automatically connects and disconnects current collectors to/from overhead contact lines during travel.
Electrically powered vehicles offer many advantages as compared to vehicles that obtain their primary source of energy from combustion engines. Since the efficiency of power storage or the clean generation of power using fuel cells is commonly considered to still be insufficient, power supply via overhead or other contact lines or via power rails provides an alternative. In rail bound vehicles such as trains or streetcars, the prior art is sufficiently practical in practice and widespread. In non-railbound vehicles (e.g., trolleybuses), the limitations of the prior art are so sizable that in many cities, existing systems have been removed and replaced with diesel-powered buses. The key limitation of existing trolleybus methods lies in their insufficient flexibility (e.g., lacking capability that may be achieved only with substantial effort and expense) to also operate the trolleybus without power from the overhead line for a brief period of time.
Electric buses (e.g., trolleybuses and catenary buses) are supplied with power via trolley poles primarily via dual-pole wire systems in the form of overhead lines. The lines are installed at a defined height, generally in the center above the designated lane. In so doing, the lines are not really parallel to one another on account of the manner in which the lines are affixed (e.g., a distance between the lines may be 60 cm and may vary within a range of ten centimeters or more). The height at which the lines are affixed is also subject to a sizable tolerance, ranging between 5 and 6 meters. An even larger tolerance is present with regard to the offset in relation to the middle of the lane, which may amount to as much as 4.5 m for 6.2 m long poles. All of these factors pose an impediment to automatic connection to the overhead line, which is a prerequisite for a series of other application scenarios that may advance the desired electrical mobility essentially enabled with a trolleybus (e.g., in inner-city areas).
The current collectors may be featured as U-shaped collector shoes with swivel action around a vertical and a horizontal axis and located at a tip of each of the two pole current collectors. The collector shoes are pressed via the poles against the overhead lines via a vertically acting upward force so that electrical contact is continuous during the connection phase.
The existing systems are configured so that the current collectors remain connected over the entire distance traveled and are disconnected or are connected only when the vehicle is stopped. Since the construction of the line networks used for the continuous supply of power during the entire journey and maintenance of the line networks (e.g., when the line networks feature overhead switches for double or multiple lines along routes with bidirectional and multi-lane traffic) are expensive, and since the line networks also involve other disadvantages such as esthetic restrictions, preventing the line networks from being installed in historical town centers or in representational areas, for example, it is desirable to operate the vehicle off-wire over more or less short distances.
An additional autonomous supply of energy is to be provided in the vehicle (e.g., via batteries, capacitors, a combustion engine with a generator, fuel cells or a flywheel), and a current collector system that is able to automatically disconnect from and, in particular, reconnect to the wires quickly and reliably is to be provided. Various developments exist that address the question of the provision of power in the vehicle (e.g., dual-mode vehicles that feature a diesel generator on board, or the flywheel energy storage device described in DE 30 15 754 C enabling the generation of power for autonomous operation).
Suggested solutions have also been published on the problem of automatic reconnection (e.g., the controlled guidance of the current collector to the wires). In DE 24 60 843, it is suggested that an engagement aid, or “lug”, be vertically installed on either side of the collector shoes running parallel to the direction of travel. The engagement aid is configured to facilitate engagement and upon the contact being established, is folded away in a downwards direction. The disadvantages of this system are that automatic connection using this device may only be made when the vehicle is stopped because the lug, when flipped out, projects into the area of the overhead wire suspension. Guiding the lug to the overhead wire requires manual interaction.
The proposal made in FR 2 506 234 provides an attempt to automate the process and thus reduce the measurement and control effort by affixing both of the current collector shoes to a common support.
The submitted solution of DE 100 54 766 solves the problem of the unreliable parallel positioning of the two overhead wires.
The related patent application of DE 100 12 039 C poses the additional disadvantage that an entirely new and more complex technology and configuration of the overhead wire positioning and suspension is presupposed.